Sensor control for apparatuses for supporting and monitoring a person

ABSTRACT

A person support apparatus includes a frame and a support surface cooperating with the frame to support a person. The person support apparatus also has a sensor coupled to one of the frame and the support surface. The sensor detects at least one characteristic associated with the person. A controller is coupled to the sensor. In response to at least one of a condition of the frame, a condition of the support surface, a position of the person, or a condition of the person, the controller operates to control the sensor by at least one of changing a gain of the sensor and changing a manner in which a signal from the sensor is filtered. In some instances, the controller turns the sensor off.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit, under 35 U.S.C. §119(e), ofU.S. Provisional Application Nos. 61/243,714; 61/243,741; 61/243,806;and 61/243,825; each of which was filed Sep. 18, 2009 and each of whichis hereby incorporated by reference herein.

The present application relates to U.S. Application No. (unknown), filedconcurrently herewith and titled “Apparatuses for Supporting andMonitoring a Condition of a Person” (attorney docket number7175-213829).

BACKGROUND

This disclosure relates to person support apparatuses such as hospitalbeds. More particularly, the present disclosure relates to personsupport apparatuses having sensors that sense one or more conditions ofthe person or of the apparatus.

Person support apparatuses include beds, chairs, stretchers, seats,mattresses, therapy surfaces, furniture, and the like, or otherapparatuses that support a person. Hospital beds and stretchers,hospital mattresses, and wheelchairs are examples of such apparatusesthat support persons. Consumer beds, chairs, and furniture are alsoexamples of such person support apparatuses, as are seats for vehicles,businesses, and venues.

Vital signs monitors monitor one or more physiological parameters of aperson, such as body temperature, pulse rate, heart rate, bloodpressure, and respiratory rate, as well as other body signs, such asend-tidal CO2, SpO2 (saturation of oxygen in arterial blood flow), andother indicators of the person's physiological state. Position andmovement detection systems monitor the position and/or movement of aperson to determine if they are attempting to exit the supportapparatus.

While various person support apparatuses have been developed, there isstill room for development. Thus, a need persists for furthercontributions in this area of technology.

SUMMARY

The present disclosure includes one or more of the features recited inthe appended claims and/or the following features which, alone or in anycombination, may comprise patentable subject matter.

A person support apparatus may include a frame and a support surfacecooperating with the frame to support a person. The person supportapparatus may also have a sensor coupled to one of the frame and thesupport surface, the sensor detecting at least one characteristicassociated with the person. A controller may be coupled to the sensor.In response to at least one of a condition of the frame, a condition ofthe support surface, a position of the person, or a condition of theperson, the controller may operate to control the sensor by at least oneof changing a gain of the sensor and changing a manner in which a signalfrom the sensor is filtered.

The controller may also be operable to turn the sensor on and off. Thesensor may include a plurality of sensors and the controller may operateto control each of the plurality of sensors by at least one of changinga gain of each of the plurality of sensors and changing a manner inwhich signals from each of the plurality of sensors is filtered. Thecontroller may operate to turn off some of the plurality of sensors andto turn on others of the plurality of sensors. The determination by thecontroller as to which sensors may be turned off and which sensors maybe turned on may be based on a position of the person relative to thesupport surface or relative to the frame. Alternatively or additionally,the determination by the controller as to which sensors may be turnedoff and which sensors may be turned on may be based on movement of afirst portion of the frame relative to a second portion of the frame.

The controller may be operable to implement via software at least one ofa high pass filter, a low pass filter, and a band pass filter and/or thecontroller may be operable to selectively switch the sensor betweenbeing coupled to a high pass filter, a low pass filter, and a band passfilter. The controller may be operable to filter out noise associatedwith at least one of a first electric component associated with thesupport surface and a second electric component associated with theframe. The controller may be operable to filter out noise associatedwith separate medical equipment in a person's room based on informationreceived from an electronic medical record (EMR) system.

The sensor may comprise a force sensing load cell coupled to the frameor a pressure sensing strip coupled to the support surface or both. Thesupport surface may comprise a mattress that may have inflatablebladders and the sensor may include a pressure sensor that measurespressure in at least one of the bladders. The sensor may sense at leastone of the person's weight, heart rate, respiration rate, andtemperature. The at least one characteristic associated with the personand sensed by the sensor my include at least one of a force profile, apressure in a bladder, and a physiological characteristic.

The controller may adjust the gain of the sensor as a function of adifference between a first position of the person relative to one of theframe and the support surface and a second position of the personrelative to one of the frame and the support surface. The controller maybe operable to prevent a user from accessing predetermined functions ofthe person support apparatus based on at least one of signal strengthand clarity of a signal from the sensor.

The sensor may include a plurality of sensors and the controller maycontrol the gain of each of the plurality of sensors such that signalstrength of an output signal of each of the plurality of sensors may besubstantially equal. The sensor may include a first sensor and a secondsensor and the controller may operate to amplify a signal from the firstsensor when signal strength of the signal from the first sensor is lessthan that of the second sensor. Alternatively or additionally, a signalfrom the first sensor may be filtered when signal clarity of the signalfrom the first sensor is less than that of the second sensor.

According to the present disclosure a system may be configured to selectbetween a first sensor and a second sensor based on at least one of theposition of a person on a person support surface, the pressure insupport surface fluid bladders, a difference between the signal strengthand/or clarity of the first sensor and a signal strength and/or clarityof a second sensor, and person support apparatus status information.Also according to the present disclosure, a system may be configured toamplify and/or filter a signal from a first sensor as a function of atleast one of a difference between the signal strength and/or clarity ofthe first sensor and a signal strength and/or clarity of a secondsensor, the position of a person on a person support surface, thepressure in support surface fluid bladders, a comparison between a firstsensor and second sensor, and person support apparatus statusinformation.

Additional features alone or in combination with any other feature(s),including those listed above and those listed in the claims and thosedescribed in detail below, may comprise patentable subject matter.Others will become apparent to those skilled in the art uponconsideration of the following detailed description of illustrativeembodiments exemplifying the best mode of carrying out the invention aspresently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the illustrative examples in the drawings, wherein likenumerals represent the same or similar elements throughout:

FIG. 1 is a perspective view of an embodiment of a person supportapparatus according to one illustrative embodiment;

FIG. 2 is perspective view of the person support surface of FIG. 1according to one illustrative embodiment partially cut away to revealsensors integrated therein;

FIG. 3 is a perspective view of the upper frame according to oneillustrative embodiment of the person support apparatus of FIG. 1;

FIG. 4 is a diagrammatic view of a control system for the person supportapparatus of FIG. 1 according to one illustrative embodiment;

FIG. 5 is a diagrammatic view of a control system for the person supportapparatus of FIG. 1 according to another illustrative embodiment;

FIG. 6 is a top view of the fluid bladders within the person supportsurface of FIG. 2 with pressure sensors coupled across the bladdersaccording to one illustrative embodiment;

FIG. 7 is a top view of the fluid bladders within the person supportsurface of FIG. 2 with pressure sensors coupled along the bladdersaccording to another illustrative embodiment;

FIG. 8 is a top view of the fluid bladders within the person supportsurface of FIG. 2 with pressure sensors integrated in the bladdersaccording to yet another illustrative embodiment;

FIG. 9 is a flowchart for a procedure that can be executed by thecontrol system of FIGS. 4 and/or 5 according to one illustrativeembodiment;

FIG. 10 is a partial diagrammatic view of a person in a first positionwith respect to the person support surface of FIG. 1 according to oneillustrative embodiment;

FIG. 11 is a partial diagrammatic view of a person in a second positionwith respect to the person support surface of FIG. 1;

FIG. 12 is a flowchart for a procedure that can be executed by thecontrol system of FIGS. 4 and/or 5 according to one illustrativeembodiment; and

FIG. 13 is a flowchart for a procedure that can be executed by thecontrol system of FIGS. 4 and/or 5 according to one illustrativeembodiment.

DETAILED DESCRIPTION

While the present disclosure can take many different forms, for thepurpose of promoting an understanding of the principles of thedisclosure, reference will now be made to the embodiments illustrated inthe drawings, and specific language will be used to describe the same.No limitation of the scope of the disclosure is thereby intended.Various alterations, further modifications of the described embodiments,and any further applications of the principles of the disclosure, asdescribed herein, are contemplated.

One illustrative embodiment of the present disclosure includes a systemconfigured to select between a first sensor and a second sensor based onat least one of the position of a person on a person support surface,the pressure in support surface fluid bladders, a difference between thesignal strength and/or clarity of the first sensor and a signal strengthand/or clarity of a second sensor, and person support apparatus statusinformation. Another illustrative embodiment includes a systemconfigured to amplify and/or filter a signal from a first sensor as afunction of at least one of a difference between the signal strengthand/or clarity of the first sensor and a signal strength and/or clarityof a second sensor, the position of a person on a person supportsurface, the pressure in support surface fluid bladders, a comparisonbetween a first sensor and second sensor, and person support apparatusstatus information.

A person support apparatus 1010 according to an illustrative embodimentof the current disclosure is shown in FIG. 1. The person supportapparatus 10 includes a head section H1, where the head and a portion ofthe torso of a person (not shown) can be positioned, and a foot sectionF1, where the feet of a person (not shown) can be positioned. The personsupport apparatus 1010 includes a lower frame 1012 or base 1012, anupper frame 1014, a plurality of supports 1016, a fluid supply 1018, anda control system 1020. In some embodiments, the person support apparatus1010 includes only one support 1016. The lower frame 1012 includes atleast one lower frame section that is supported by casters 1022 as shownin FIG. 1.

The person support apparatus 1010 supports a person support surface 1024or mattress 1024 on the upper frame 1014 as shown in FIGS. 1, 2, & 6-8.The person support surface 1024 is configured to support a person (notshown) in multiple articulated positions. The person support surface1024 includes a back portion B1 and a main portion M1. The personsupport surface 1024 includes a cover 1026 or ticking 1026 thatenvelopes one or more support sections and/or layers having foam and/orfluid bladders 1028. The person support surface 1024 is configured todeliver therapy to the person, such as, for example, through sequentialinflation/deflation of the fluid bladders 1028, rapid changes inpressure of the fluid in the fluid bladders 1028, and/or passing fluidthrough the person support surface 1024. For example, one or moreportions of the surface 1024 provides alternating pressure therapy,continuous lateral rotation therapy, low air loss therapy, boostassistance, percussion/vibration therapy, and/or other therapies. Insome contemplated embodiments, the person support surface 1024 includesa coverlet (not shown) that overlies another person support surface 1024and that is configured to deliver therapy to a person supported thereon.

The supports 1016 are coupled with the upper frame 1014 and the lowerframe 1012 and define a vertical axis Z1 that extends through the lowerframe 1012 and the upper frame 1014 substantially perpendicular when thelower frame 1012 and the upper frame 1014 are parallel one another asshown in FIG. 1. In the illustrative example, the supports 1016 are liftmechanisms 1016 with a lift driver (not shown) that causes the liftmechanisms 1016 to expand and/or contract to raise and/or lower theupper frame 1014 with respect to the lower frame 1012. In someembodiments, the supports 1016 include at least one of telescopingtowers, scissor lifts, rotational lifts, hydraulic lifts or actuators,pneumatic lifts or actuators, linear actuators, electronic actuators,chain lifts, or other lift mechanisms. In some embodiments, the supports1016 comprise at least one fixed column (not shown). According to someembodiments, the supports 1016 move the upper frame 1014 to aTrendelenburg/reverse Trendelenburg position and/or rotate the upperframe 1014 from side to side with respect to the lower frame 1012.

The upper frame 1014 defines a longitudinal axis X1 that extends atleast the length of the person support apparatus 1010 through the headend H1 and the foot end F1 along the lateral center of the upper frame1014, and a lateral axis Y1 that is perpendicular to the longitudinalaxis X1 and extends at least the width of the person support apparatus1010 through the longitudinal center of the upper frame 1014 as shown inFIGS. 1 and 3. The upper frame 1014 includes a deck 1030, anintermediate frame 1032, and an upper frame base 1034 coupled to thesupports 1016 which support the deck 1030 and the intermediate frame1032. In some embodiments, the upper frame 1014 also includes afootboard FB, a head board HB, and/or siderails SR supported by theintermediate frame 1032. In some embodiments, the upper frame 1014 onlyincludes a deck 1030. The deck 1030 has multiple sections, such as, ahead deck section HD, a seat deck section SD, and a foot deck sectionFD, that are pivotably coupled to one another and/or the deck 1030 andarticulate about the lateral axis Y1.

The fluid supply 1018 couples to the person support surface 1024 througha conduit C1 and is configured to supply fluid to the fluid bladders1028 of the person surface 1024 as shown in FIG. 3. In some embodiments,the fluid supply 1018 also supplies fluid to the coverlet (not shown).In some embodiments, the fluid supply 1018 supplies gas to the personsupport surface 1024. The fluid supply 1018 includes a fluid source (notshown) such as an air blower (not shown) or an air compressor (notshown). The fluid supply 1018 includes a user interface (not shown)and/or a controller (not shown) that controls the operation of the fluidsource in response to an input from a user or control system, such as,control system 1020.

The control system 1020 includes a plurality of sensors 1036 and controlmodules 1038 as shown in FIGS. 5 and 6. In some embodiments, the controlsystem 1020 is configured to control various functions of the personsupport apparatus 1010 including, but not limited to, for example,articulating the deck 1030 with respect to the intermediate frame 1032,administering therapy to a person supported on the person supportapparatus 1010, alerting caregivers when a person is exiting the personsupport apparatus 1010, alerting caregivers when a person is out of adesired position relative to the person support surface 1024, outputinformation processed by the control system 1020 to a display (notshown), etc. The control system 1020 is coupled to the upper frame 1014ins some instances. In other instances, the control system 1020 iscoupled to the lower frame 1012, supports 1016, a siderail, and/orelsewhere on the person support apparatus 1010. In further embodiments,the control system 1020 is incorporated within or coupled to the personsupport surface 1024. In some embodiments, the control modules 1038 areintegrated into a graphical user interface (not shown). In otherembodiments, the control system 1020 is integrated into an externalnetwork (not shown), such as, a hospital network, in communication withthe person support apparatus 1010.

The sensors 1036 are operatively coupled to the control modules 1038 andare configured to sense various parameters, including, but not limitedto, for example, a person's physiological information, a position of aperson on the person support apparatus 1010 and/or person supportsurface 1024, a pressure of the fluid inside the bladders 1028 in theperson support surface 1024, or other various parameters. In someembodiments, the sensors 1036 comprise force sensors 1040 that arecoupled to the upper frame 1014 and that are configured to measure forceon the upper frame 1014 as shown in FIGS. 5 and 6. In some embodiments,the sensors 1036 are force sensors 1040 that are configured to measureforce on the upper frame 1014 and that are positioned between theintermediate frame 1032 and the upper frame base 1034 so as to couplethe intermediate frame 1032 and deck 1030 to the upper frame base 1034.

In some contemplated embodiments, the sensors 1036 are force sensors1040 that are integrated into the person support surface 1024 and thatare configured to measure changes in force on the person support surface1024 as shown in FIG. 2. In some embodiments, the force sensors 1040 arecoupled to the supports 1016 and/or the lower frame 1012. In furtherembodiments, the sensors 1036 are integrated into the casters 1022and/or are engaged by the casters 1022. It is within the scope of thisdisclosure for the sensors 1036 to be integrated into the ticking 1026such as being between the layers of the ticking 1026. In someembodiments, the force sensors 1040 are load cells 1040 that are coupledproximate the corners of the intermediate frame 1032. In someembodiments, the force sensors 1040 are piezoelectric sensors and/orelongated sensor strips or arrays. In other embodiments, the forcesensors 1040 are other types of force sensors 1040 and are positioned inother locations on the upper frame 1014 and/or within the person supportsurface 1024.

In some embodiments, the sensors 1036 are pressure sensors 1042 that areintegrated into the person support surface 1024 and that are configuredto measure the pressure in/among the fluid bladders 1028 in the personsupport surface 1024 as shown in FIGS. 6-8. In some embodiments, thepressure sensors 1042 are coupled between the bladders 1028 such thatthey allow communication between adjacent bladders 1028. It someembodiments, the pressure sensors are situated within the bladders 1028and measure the pressure within the bladder 1026.

In some embodiments according to this disclosure, the sensors 1036 arephysiological sensors 1044 that are integrated into the person supportsurface 1024 and that are configured to measure one or morephysiological parameters of a person supported on the person supportsurface 1024 as shown in FIG. 2. For example, one or more of the forcesensors 1040 and one or more of the pressure sensors 1042 sensedifferent physiological parameters in some embodiments. In someembodiments, the physiological sensors 1044 are used to sense the heartrate and/or respiration rate of a person supported on the person supportsurface 1024. Alternatively or additionally, one or more of thephysiological sensors 1044 sense the temperature of the person. It alsocontemplated by this disclosure for the physiological sensors 1044 to beconfigured to sense the movement and/or weight of the person on theperson support surface 1024. In some embodiments, one or more of thephysiological sensors 1044 are configured to sense the relative humidityof a tissue on the person support surface 1024. In some embodiments, thephysiological sensors 1044 are pressure-strip sensors disposed on thefluid bladders 1028 along an axis parallel with the lateral axis Y1and/or along an axis parallel with the longitudinal axis X1.

The control modules 1038 are each configured to perform differentoperations in the illustrative example. However, in some embodiments, asingle control module 1038 is configured to perform the multipledifferent operations. In some embodiments, a single control module 1038is configured to perform operations independently or in conjunction withat least one other control module 1038. In some embodiments, a firstcontrol module 1038, such as, a person position monitor module 1046(PPM), is configured to detect the position of a person on the personsupport apparatus 1010. In some such embodiments, a second controlmodule 1038, such as a therapy control module 1048, is configured tosense and/or modify the pressure within the fluid bladders 1028. Infurther such embodiments, a third control module 1038, such as aphysiological parameter monitor module 1050, is configured to detect aperson's physiological information.

In some embodiments, the control modules 1038 are operatively coupledtogether through a network 1052 as shown in FIGS. 4 and 5. The network1052 facilitates communication between the various modules and/orequipment connected to the network 1052. In some embodiments, thenetwork 1052 is a CAN network on a person-support apparatus 1010.Alternatively or additionally, the network 1052 comprises a hospitalnetwork (not shown). In some embodiments, the network 1052 includesother types of networks or communication protocols that facilitatecommunication between two or more devices. It is contemplated by thisdisclosure that the modules 1038 can be configured to connect to thenetwork 1052 wirelessly, if desired. In some embodiments, the controlmodules 1038 negotiate with the network 1052 to be a network node. Insome embodiments, the control modules 1038 are located at or on any nodeon the network 1052 and/or distributed across multiple nodes on thenetwork 1052.

The control modules 1038 are implemented using software and/or hardware.In some embodiments, the control modules 1038 are implemented insoftware and are configured to perform one or more operations as shownin FIGS. 4 and 5. In some embodiments, the modules 1038 are configuredto communicate via a memory mailbox where information from one module issent to the memory address of a recipient module. In other embodiments,the software modules are configured to push information to a memorylocation, such as, a stack, that the control modules 1038 monitor orperiodically check for information that the software modules subscribeto.

In some embodiments, the control modules 1038 are implemented usinghardware. In some such embodiments, the control modules 1038 include acontroller 1054 or processor 1054 and memory 1056 as shown in FIGS. 4and 5. The controller 1054 is provided as a single component or acollection of operatively coupled components; and is comprised ofdigital circuitry, analog circuitry, or a hybrid combination of both ofthese types. When of a multicomponent form, controller 1054 has one ormore components remotely located relative to the others in someinstances. The controller 1054 includes, for example, multipleprocessing units arranged to operate independently, in a pipelineprocessing arrangement, in a parallel processing arrangement, and/orsuch different arrangement as would occur to those skilled in the art.In some embodiments, processor 1054 is a programmable microprocessingdevice of a solid-state, integrated circuit type that includes one ormore processing units and memory. It is within the scope of thisdisclosure for the controller 1054 to include one or more signalconditioners, modulators, demodulators, Arithmetic Logic Units (ALUs),Central Processing Units (CPUs), limiters, oscillators, control clocks,amplifiers, signal conditioners, filters, format converters,communication ports, clamps, delay devices, memory devices, and/ordifferent circuitry or functional components as would occur to thoseskilled in the art to perform the desired communications. In someembodiments, the controller 1054 includes a computer network interfaceto communicate among various system components and/or components notincluded in the depicted system, as desired. The listed examples are notintended to be an exhaustive list of structures that are within thescope of controller 1054, but are instead only a non-exhaustive list ofsuch structures which can have substantial differences in the manner inwhich they are implemented and/or operate.

The controller 1054 is operatively coupled with the sensors 1036 andreceives information from the sensors 1036. In some embodiments, one ormore of the sensors 1036 are operatively coupled to the network 1052 andthe controller 1054 receives the information from the sensors 1036 andoutputs from other modules 1038 via the network 1052. In someembodiments, one or more of the sensors 1036 are configured to producean analog data signal and are connected directly to the controller 1054.Alternatively or additionally, one or more of the sensors 1036 areconfigured to produce a digital data signal, e.g., a serial digital datasignal, that is transmitted to the network 1052, e.g., a SerialPeripheral Interface (SPI) network 1052, to communicate with thecontroller 1054. The signals are stored in the memory 1056, which isoperatively coupled with the controller 1054. In some embodiments, thememory 1056 is integrated into the controller 1054.

The controller 1054 is configured to execute operating logic 1058 thatdefines various control, management, and/or regulation functions asshown in FIGS. 9, 12 and 13. In some embodiments, the softwareimplemented modules include operating logic 1058. The operating logic1058 is in the form of software, firmware, and/or dedicated hardware,such as, a series of programmed instructions, code, electronic files, orcommands using general purpose or special purpose programming languagesor programs executed on one or more general purpose or special purposecomputers, processors, other control circuitry, or networks; a hardwiredstate machine; and/or a different form as would occur to those skilledin the art.

In some embodiments, one of the control modules 1038 is a patientposition monitoring (PPM) module 1046. The memory 1056 of the controller1054 includes operating logic 1058 with a number of software algorithmsand other data that is executed by the controller 1054 to monitorpatient movement relative to a reference load cell 1040 distribution,impending exit from the person support surface 1024 and/or exittherefrom. In some embodiments, the operating logic 1058 for managingsuch functions is in accordance with FIG. 5 in the form of a combinedflowchart and/or state machine. The operating logic 1058 is executedperiodically by the controller 1054, e.g., once every 200 ms, to monitorpatient movement relative to a reference load cell 1040 distribution,impending exit from the mattress 1024 and/or exit from the mattress1024. Referring to FIG. 5, the operating logic 1058 begins with thecontroller 1054 determining whether the person position monitor module1046 is armed, i.e., whether one of the patient monitoring modes wasactive, before the last power down of the person position monitor module1046.

The patient monitoring modes includes a patient movement (PM) modewherein the person position monitor module 1046 is operable to monitormovement of a patient on the mattress 1024 by monitoring weightdistribution among two or three of the four load cells 1040 relative toa predefined set of PM load cell threshold data, a patient exit (PE)mode wherein the person position monitor module 1046 is operable tomonitor impending exit from the mattress 1024 by monitoring weightdistribution of the four load cells 1040 relative to a predefined set ofPE load cell threshold data, and a patient out-of-bed (OOB) mode whereinthe person position monitor module 1046 is operable to monitor exit ofthe patient from the mattress 1024 by monitoring the patient weightdistributed over the four load cells 1040 relative to an armed patientweight, wherein the armed weight corresponds to the patient weightdistributed over the four load cells 1040 when the patient monitoringmode was armed as will be described in greater detail hereinafter. Inany case, if the controller 1054 determines that the person positionmonitor module 1046 was not armed before the last system power down,execution of the operating logic 1058 causes the controller 1054 toexecute a state machine preparation routine. If the controller 1054instead determines that the person position monitor module 1046 wasarmed before the last system power down, execution of the operatinglogic 1058 advances to an Arming From Power Up Transition State of thestate machine where the patient weight is processed to determine whetherit is contained within a defined armed range prior to advancing to thePM Active State of the state machine to resume operation of the patientmonitoring mode that was active at the last system power down. Oneexample of such a system can be found in U.S. Pat. No. 7,253,366 toBhai, issued on Aug. 7, 2007.

In some embodiments, the controller 1054 detects the ingress/egress of aperson to/from the person-support apparatus 1010 by determining thecenter of gravity of the weight thereon. One example of such a systemcan be found in U.S. Pat. No. 5,276,432 to Travis, issued on Jan. 4,1994. In still another illustrative embodiment, the controller 1054treats the upper frame 1014 as though it were disposed within ahorizontal plane, extracts from the weight value measured by each loadcell 1040 a portion which represents the weight of a patient, uses theextracted portions to calculate the location within the plane of acenter of gravity of the patient, determines whether the location of thecenter of gravity is inside or outside a predetermined region which is aportion of the plane, and initiates an alarm when it is found that thecenter of gravity is located outside the predetermined region. Oneexample of such a system can be found in U.S. Pat. No. 5,276,432.

In some embodiments, the controller 1054 of the PPM module 1046 includesoperating logic 1058 in the form of procedure 1060, for example, asshown in the flowchart of FIG. 9. Procedure 1060 includesoperations/conditionals shown in blocks 1062, 1064, 1066, 1068, 1070,and 1072. Procedure 1060 evaluates changes in the force profile (FP) forthe surface 1024 as a function of the difference between the last sensedforce values (LSFV) and the newly sensed force values (NSFV) asrepresented by the following equation:

${\Delta \; F\; {P\begin{bmatrix}A & B \\C & D\end{bmatrix}}} = {{L\; S\; F\; {V\begin{bmatrix}A_{L} & B_{L} \\C_{L} & D_{L}\end{bmatrix}}} - {N\; S\; F\; {V\begin{bmatrix}A_{N} & B_{N} \\C_{N} & D_{N}\end{bmatrix}}}}$

Procedure 1060 begins with the operation of block 1062 where, in someembodiments, the force sensors 1040 post an electronic data signalrepresenting at least one of an event and an amount of force on thenetwork 1052. In some embodiments, the force sensors 1040 post datasignals continuously and/or over at predetermined intervals.Alternatively or additionally, the force sensors 1040 post data signalsin response to a query from a PPM module 1046. In some embodiments, thedata signals include information that identifies what operations and/orcontrol modules 1038 the data can be utilized by. It should also beappreciated that posting can mean sending data out on a network. In someembodiments, the sensors 1036 are operatively coupled directly tospecific control modules 1038, for example, the force sensors 1040 beingoperatively coupled to the PPM module 1046, the pressure sensors 1042being operatively coupled to a therapy control module 1048, and thephysiological sensors 1044 being operatively coupled to a physiologicalparameter monitor module 1050.

In the conditional of block 1064, the PPM module 1046 examines the datasignal posted by the force sensors 1040 on the network 1052 anddetermines whether or not the PPM module 1046 performs any operationsthat utilize the data as an input, i.e., whether or not the PPM module1046 subscribes to the data signal. Other control modules 1038, such as,the therapy control module 1048 and/or the physiological parametermonitor module 1050, also subscribe to the force sensor 1040 data signaland receives the data as an input, while control modules 1038 that donot subscribe to the data disregard the data and wait for data signalsto be posted that they do subscribe to.

In the operation of block 1066, the controller 1054 of the PPM module1046 inputs the data into the control logic 1058 that utilizes the dataas an input. In the PPM control logic 1058, the controller 1054 storesthe posted data in the memory 1056 and compares previously posted dataand newly input data to determine changes in the force profile of aperson on the surface 1024, i.e., determine if and where a person hasmoved with respect to the surface 1024.

In the conditional of block 1068, the controller 1054 determines ifchanges in the force profile are greater than a predetermined threshold.Changes in the force profile can potentially signify that the person ispositioned higher on the surface 1024, i.e., more toward the head end H1of the person support apparatus 1010, than desired; or that the personis positioned lower on the surface 1024, i.e., more toward the foot endF1 of the person support apparatus 1010, than desired. See FIGS. 10 and11. In some embodiments, changes in the force profile is used todetermine whether the person has moved to a side of the surface 1024and/or how much they have moved with respect to the surface 1024. Such adetermination is helpful in predicting whether the person is going toexit the person support apparatus 1010, adjusting the sensitivity of thesensors 1036 to compensate for movement, when a person is beginning towake up, and/or whether continued therapy in the new/current position isdesirable, or various other situations.

In the conditional of block 1070, if the controller 1054 determined inthe conditional of block 1068 that the change in the force profileexceeded the predetermined threshold, the controller 1054 proceeds todetermine whether or not the PPM system is armed, i.e., whether or notthe PPM module 1046 is set to monitor the position of the person on theperson support apparatus 1010. In some embodiments, a caregiver and/orthe person on the person support apparatus 1010 activates anddeactivates the PPM system locally through a caregiver interface on theperson support apparatus 1010 or remotely. If the PPM system is armed,then the controller 1054 generates an alert signal in the operation ofblock 1072 to alert a caregiver that the person on the person supportapparatus 1010 is about to exit the person support apparatus 1010. Insome embodiments, the controller 1054 also communicates the amount theperson has moved with respect to the person support apparatus 1010. Thecontroller 1054 communicates the alert signal wirelessly or over ahospital network or an adverse condition alert system, such as, theNavicare® system sold by Hill-Rom Company, Inc., a caregiver station, amobile paging device, a cellular phone, a pendant, over an intercom, orthrough other caregiver notification methods and devices. If the PPMsystem is not armed, then the controller 1054 returns to the operationof block 1062. In some embodiments, the controller 1054 generatessignals representative of an event, e.g., the person has moved towardthe head section H1, and/or an amount that the person has moved withrespect to the person support apparatus 1010 and post the signals backon the network 1052 before returning to operation 1062 since othercontrol modules 1038 can subscribe to the output of the PPM module 1046.In some embodiments, the controller 1054 prevents a user from accessingspecific features on a user interface (not shown) based on themovement/positioning of the person on the person support surface 1024.

In some embodiments, one of the control modules 1038 is a therapycontrol module 1048. The therapy control module 1048 is operativelycoupled to the pressure sensors 1042 and the fluid supply 1018. In someembodiments, the therapy control module 1048 controls various therapiesthat are administered to the person, such as, lateral rotation,percussion vibration, low air loss, or other therapies. The therapycontrol module 1048 includes operating logic 1058 in the form ofprocedure 1074, for example, as shown in the flowchart of FIG. 12.Procedure 1074 includes the operations/conditionals of blocks 1076,1078, 1080, 1082, and 1084. Procedure 1074 evaluates changes in thepressure profile (PP) for the surface 1024 as a function of thedifference between the last sensed pressure values (LSPV) and the newlysensed pressure values (NSPV) as represented by the following equation:

ΔPP[P]=LSPV[P _(L)]−NSPV[P _(N)]

Procedure 1074 begins with the operation of block 1076 where, in someembodiments, the pressure sensors 1042 post an electronic data signalrepresenting at least one of an event and an amount on the network 1052.In the conditional of block 1078, the therapy control module 1048examines the data signal posted by the pressure sensors 1042 on thenetwork 1052 and determines whether or not the therapy control module1048 performs any operations that utilize the data as an input, i.e.,whether or not the therapy control module 1048 subscribes to the datasignal.

In the operation of block 1080, the controller 1054 of the therapycontrol module 1048 inputs the data into the control logic that utilizesthe data as an input. In some embodiments, the controller 1054 of thetherapy control module 1048 inputs the data into the therapy controllogic 1058. In the therapy control logic 1058, the controller 1054stores the posted data in the memory 1056 and compares previously posteddata and newly input data to determine changes in the pressure profileof a person on the surface 1024, i.e., determine if, where, and by howmuch a person has moved with respect to the surface 1024.

In the conditional of block 1082, the controller 1054 determines ifchanges in the force profile are greater than a predetermined threshold.Changes in the pressure profile can potentially signify that the personis positioned higher on the surface 1024, i.e., more toward the head endH1 of the person support apparatus 1010, than desired; or that theperson is positioned lower on the surface 1024, i.e., more toward thefoot end F1 of the person support apparatus 1010, than desired. In someembodiments, changes in the pressure profile is used to determinewhether the person has moved toward a side of the surface 1024 and/orhow much they have moved with respect to the surface 1024. Such adetermination is helpful in predicting whether the person is going toexit the person support apparatus 1010 and/or whether therapy in thecurrent position or a new position is desirable.

In the operation of block 1084, if the controller 1054 determined in theconditional of block 1082 that the change in the force profile exceededthe predetermined threshold, the controller 1054 cooperates with thefluid supply 1018 to modify various characteristics of the supportsurface 1024. In some embodiments, the controller 1054 cooperates withthe fluid supply 1018 to adjust the pressure of the fluid within thefluid bladders 1028 as a function of the movement. In some embodiments,the pressure in the fluid bladders 1028 is changed to maintain a comfortlevel of a person by reducing the pressure in some bladders 1028 andincreasing the pressure in other bladders 1028 to compensate for themovement of the person. In some embodiments, the controller 1054cooperates with the fluid supply 1018 to adjust a therapy, such as,continuous lateral rotation, percussion vibration, or other therapies,as a function of the movement. In some embodiments, the therapy isstopped completely or at least until the person moves back to within apredetermined range of the previous position. In some embodiments, thecontroller 1054 generates signals representative of an event, e.g., thepressure profile has changed, which can potentially signify movement ofthe person with respect to the surface 1024, and/or an amount that thepressure has increased, or an amount the pressure profile has changedand post the signals back on the network 1052 before returning tooperation 1076, since other control modules 1038 subscribe to the outputof therapy control module 1048 in some instances.

In some embodiments, one or more of the control modules 1038 are aphysiological parameter monitor module 1050. The physiological parametermonitor module 1050 is operatively coupled with the physiologicalsensors 1044. The physiological parameter monitor module 1050 includesoperating logic 1058 in the form of procedure 1086. In some embodiments,procedure 1086 evaluates changes in the physiological sensor signalstrength and/or clarity (PS) for the surface 1024 to determine whether afirst physiological sensor 1044 would provide a more desirable signaland should be used instead of a second physiological sensor 1044. Thus,according to this disclosure, one or more of some sensors 1044 areturned on and one or more of others are turned off depending upon whichsensors have or are expected to have the best quality data signals.Information from the PPM system of the person support apparatus, forexample, may be used to determine that the sensors 1044 on the left halfof the apparatus should be turned on and the sensors on the right half1044 should be turned off based on the position of the patient beingmore toward the left half of the apparatus, or vice versa. Other subsetsof the sensors may be turned on and off in other scenarios such as, forexample, turning on sensors in a seat section if the PPM systemindicates that the patient is likely sitting up while turning offsensors in zones or sections of the person support apparatus that are nolonger supporting a person.

In some embodiments, procedure 1086 evaluates the changes in the PS as afunction of the difference between a first physiological sensor signalstrength and/or clarity (FPS) and a second physiological sensor signalstrength and/or clarity (SPS) as represented by the following equation:

ΔPS[S]=FPS[S _(L)]−SPS[S _(N)]

In other embodiments, procedure 1086 subscribes to data on the network1052 and uses the data to determine what sensor 1036 or sensor array1036, i.e., physiological sensor 1044 or sensor array 1044, should beactivated or turned on to obtain the most desirable physiologicalsignal. In some embodiments, procedure 1086 subscribes to output signalsfrom the PPM module 1046 regarding the position of the person withrespect to the surface 1024 and causes the physiological parametermonitor module 1050 to activate and/or receive input signals fromdifferent sensors 1036 as a function of the position of the person. Insome embodiments, procedure 1086 subscribes to data on the network 1052corresponding to the angle of articulation of the head deck section HDand causes the physiological parameter monitor module 1050 to activateand/or receive input signals from different sensors 1036 as a functionof the angle of articulation of the head deck section HD. For example,depending upon the angle of articulation of the head deck section HD,the physiological parameter monitor module 1050 activates and/orreceives input signals from a first sensor when the angle ofarticulation of the head deck section HD is less than a first angle andactivates and/or receives input signals from a second sensor when theangle of articulation of the head deck section HD is greater than orequal to a second angle. In some embodiments, the angle is about 30°.

According to this disclosure, procedure 1086 includes theoperations/conditionals of blocks 1088, 1090, 1092, 1094, 1096, and 1098as shown in the flowchart of FIG. 13. Procedure 1086 begins withoperation 1088 where, in some embodiments, a first physiological sensor1044 posts an electronic data signal representing at least one of anevent and an amount on the network 1052. In the conditional of block1090, the controller 1054 examines the data signal posted by a firstphysiological sensor 1044 and determines whether or not thephysiological parameter monitor module 1050 performs any operations thatutilize the data as an input, i.e., whether or not the physiologicalparameter monitor module 1050 subscribes to the data signal. If thecontroller determines that the module 1050 subscribes to the data, thefirst signal is stored in the memory 1056.

In the operation of block 1092, the controller 1054 deactivates thefirst physiological sensor 1044 and activates a second physiologicalsensor 1044. In some instances, the first physiological sensor 1044 andthe second physiological sensor 1044 can both be active. Deactivating orturning off a sensor within the scope of this disclosure includes atleast one of receiving information from the sensor but not using it,blocking and/or breaking communication with the sensor, and/or cuttingpower to the sensor. The second physiological sensor 1044 posts anelectronic data signal representing at least one of an event and anamount on the network 1052 in some instances.

In the conditional of block 1094, the controller 1054 examines the datasignal posted by a second physiological sensor 1044 and determineswhether or not the physiological parameter monitor module 1050subscribes to the data signal. If the controller 1054 determines thatthe module 1050 subscribes to the data, the first signal is stored inthe memory 1056. In the conditional of block 1096, the controller 1054compares the first sensed signal with the second sensed signal.

In the operation of block 1098, if the controller 1054 determines thatthe signal from the first physiological sensor 1044 has a higher signalstrength, i.e., amplitude, and/or clarity than the signal generated bythe second physiological sensor 1044, the controller deactivates thesecond physiological sensor 1044 and re-activate the first physiologicalsensor 1044. In some instances, both physiological sensors 1044 aresimultaneously active. If the controller 1054 determines that the signalfrom the first physiological sensor 1044 has a lower signal strengthand/or clarity than the signal generated by the second physiologicalsensor 1044, the controller 1054 continues to receive signals from thesecond physiological sensor 1044 in some embodiments. In someembodiments, if the controller 1054 determines that the signal from thefirst physiological sensor 1044 has a lower signal strength and/orclarity than the signal generated by the second physiological sensor1044, the controller 1054 amplifies and/or filters the signal generatedby the first physiological sensor 1044 to increase the signal strengthand/or clarity of the first physiological sensor 1044.

In the conditional of block 1100, the controller determines if thedifference between the first physiological sensor signal strength and/orclarity and the second physiological sensor signal strength and/orclarity is greater than a predetermined threshold. If the difference isgreater than the predetermined threshold, then the controller 1054generates an alert signal in operation 1102 to alert a caregiver. Insome embodiments, the controller 1054 also communicates the value of thephysiological sensor 1044 and posts back the value on the network 1052.In some embodiments, the controller 1054 communicates the alert signalwirelessly or over a hospital network or an adverse condition alertsystem, such as, the Navicare® system sold by Hill-Rom Company, Inc., acaregiver station, a mobile paging device, a cellular phone, a pendant,over an intercom, or through other caregiver notification methods anddevices. If the difference between the first physiological sensor signalstrength and/or clarity and the second physiological sensor signalstrength and/or clarity is not significant, then the controller 1054returns to the operation of block 1088.

In some embodiments, the controller 1054 generates signalsrepresentative of the difference between the first physiological sensorsignal strength and/or clarity and the second physiological sensorsignal strength and/or clarity and posts the signals back on the network1052 before returning to the operation of block 1088 because othercontrol modules 1038 subscribe to the output of the physiologicalparameter monitor module 1050 in some instances. In some embodiments,the controller 1054 prevents a user from accessing specific features ona user interface (not shown) based on the first physiological sensorsignal strength and/or clarity and the second physiological sensorsignal strength and/or clarity of the person on the person supportsurface 1024.

As mentioned above, the sensitivity of a signal form a sensor, such assensors 1040, 1042, 1044, is adjusted to improve its signal strengthand/or clarity. One way of accomplishing this is to change the gain ofthe sensor 1040, 1042, 1044. One gain change technique is to useswitches, such as transistors or micro-switches to selectively opencircuit or close circuit various parallel resistors in a feedback loopof a respective operational amplifier circuit to which signals fromsensors 1040, 1042, 1044 are input. Thus, the operational amplifiercircuit in such embodiments is considered to be part of the sensor. Useof transistors or micro-switches that are selectively activated ordeactivated to couple the signals from sensors 1040, 1042, 1044 to oneor more filters, such as a high pass filter, a low pass filter and/or aband pass filter is also contemplated by this disclosure. Digital signalprocessors that are programmable to implement one or more high passfilters, low pass filters, and/or band pass filters are also within thescope of this disclosure.

According to this disclosure, sensors that are included in personsupport apparatus 1010 and that have gain change and filteringcapabilities associated therewith include moisture sensors, acousticsensors, flow rate sensors, temperature sensors, force sensors, andpressure sensors, just to name a few. The frequency or frequencies thatare filtered out from the signals of sensors 1040, 1042, 1044 include,for example, those associated with a motor that moves one portion ofapparatus 1010 relative to another portion (e.g., deck articulationmotors, such as linear actuators, or lift system motors), thoseassociated with components of a pneumatic system of apparatus 1010(e.g., blowers or compressors used to inflate mattress 1024), thoseassociated with room ventilation equipment or fans, those associatedwith mechanical noise (e.g., bearing noise curing deck articulation),and those associated with separate medical equipment such as patientventilators, IV pumps, passive motion machines, and the like.

In some embodiments, control system 1020 of apparatus 1010 receivesinformation from a remote computer, such a computer associated with anelectronic medical records (EMR) system to determine what types ofseparate medical equipment is being used with a particular person. Basedon that information, system 1020 determines the appropriate frequency orfrequencies to filter out from the signals from one or more of sensors1040, 1042, 1044. A look-up table, for example, is provided in memory ofcontrol system 1020 with a list of “noise” frequencies associated withvarious types of medical equipment that are commonly used with personsto be supported on apparatus 1010. Alternatively or additionally, system1020 performs its own analysis of signals from sensors 1040, 1042, 1044before and after a particular component or piece of equipment startsoperating or running and then determines the frequency or frequencies ofthe noise introduced into the signal as a result of the operation of thecomponent or equipment. Thereafter, the appropriate frequency orfrequencies is/are filtered out of the signals from sensors 1040, 1042,1044. Alternatively or additionally, system 1020 adjusts the thresholdcriteria for sending alerts to caregivers depending upon whetherparticular components or pieces of equipment are being used.

In some embodiments, the control system 1020 is configured to change itsoperational characteristics based on the status of the person-supportapparatus 1010 and/or the status of devices (not shown) coupled to theperson-support apparatus 1010 and/or coupled to the person supported onthe person-support apparatus 1010. In one example, the controller 1054receives an input indicative that the angle of the head section of thedeck has changed. In this example, the controller 1054 is configured tostop receiving input signals from a sensor coupled to the head sectionand start receiving signals from a sensor in the seat section, applyvarious filters, such as, band-pass, low-pass, and/or high-pass filters,to the input signal to eliminate undesired noise, or increases/decreasesthe gain of the sensor as a function of the angle of the head section.In some instances, the sensor coupled to the head section is deactivatedand the sensor in the seat section is activated. In some embodiments,the controller looks up a device in a look-up table and/or compares thesignal prior to a change in status of the signal with the signal afterthe change in status to determine what noise the change in status mighthave introduced into the signal to determine the appropriate filter(s)to apply.

In another example, the controller 1054 receives an input indicativethat continuous lateral rotation therapy is being administered by theperson support apparatus 1010. Continuous lateral rotation therapy isused to rotate an occupant side to side to help reduce the risk ofdeveloping pressure ulcers. In some embodiments, continuous lateralrotation is implemented through the inflation and/or deflation of fluidbladders in the mattress and/or by rotating the upper frame about thelongitudinal axis X1. In this example, the controller 1054 is configuredto stop receiving input signals from a sensor coupled to one of thelateral sides of the person-support apparatus and start receivingsignals from a sensor coupled to the other of the lateral sides of theperson-support apparatus, apply various filters, such as, band-pass,low-pass, and/or high-pass filters, to the input signal to eliminateundesired noise, and/or increase/decrease the gain of the sensor as afunction of the lateral rotation. Thus, the sensor coupled to oradjacent one of the lateral sides is deactivated and the sensor coupledto or adjacent the other of the lateral sides is activated. According tothis disclosure, the activation/deactivation, filtering, and/or gainincrease/decrease is applied to individual sensors in an array ofsensors where more than one sensor is communicating signals to thecontroller.

In another example, the controller 1054 receives an input indicative ofthe status of a device coupled to the person-support apparatus and/orthe person on the person-support apparatus. The information that anotherdevice is coupled to the person and/or person-support apparatus issometimes available from the EMR or is sometimes input by a caregiver.In some instances, the device is in electronic communication, such aswireless or wired communication, with the person support apparatus 1010.In this example, the controller 1054 is configured to apply variousfilters, such as, band-pass, low-pass, and/or high-pass filters, to theinput signal to eliminate undesired noise and/or change the gain of thesensors as a function of the device. As mentioned above, the controllerlooks up the needed information concerning the device in a look-up tableand/or compares the signal prior to change in status with the signalafter the change in status to determine what noise the change in statusmight have introduced to the signal to determine the appropriatefilter(s) to apply. The controller 1054 also adjusts the parameters forany alarms that have been activated on the person-support apparatus,such as, PPM. In some embodiments, the controller 1054 modifies theoperation of a single sensor or individual sensors in an array ofsensors.

Any theory, mechanism of operation, proof, or finding stated herein ismeant to further enhance understanding of principles of the presentdisclosure and is not intended to make the present disclosure in any waydependent upon such theory, mechanism of operation, illustrativeembodiment, proof, or finding. It should be understood that while theuse of the word preferable, preferably or preferred in the descriptionabove indicates that the feature so described can be more desirable, itnonetheless can not be necessary and embodiments lacking the same can becontemplated as within the scope of the disclosure, that scope beingdefined by the claims that follow.

In reading the claims it is intended that when words such as “a,” “an,”“at least one,” “at least a portion” are used there is no intention tolimit the claim to only one item unless specifically stated to thecontrary in the claim. When the language “at least a portion” and/or “aportion” is used the item can include a portion and/or the entire itemunless specifically stated to the contrary.

While embodiments of the disclosure have been illustrated and describedin detail in the drawings and foregoing description, the same are to beconsidered as illustrative and not restrictive in character, it beingunderstood that only the selected embodiments have been shown anddescribed and that all changes, modifications and equivalents that comewithin the spirit of the disclosure as defined herein or by any of thefollowing claims are desired to be protected.

1. A person support apparatus comprising: a frame and a support surfacecooperating with the frame to support a person; a sensor coupled to oneof the frame and the support surface, the sensor detecting at least onecharacteristic associated with the person; and a controller coupled tothe sensor; wherein in response to at least one of a condition of theframe, a condition of the support surface, a position of the person, anda condition of the person, the controller operates to control the sensorby at least one of changing a gain of the sensor and changing a mannerin which a signal from the sensor is filtered.
 2. The person supportapparatus of claim 1, wherein the controller is also operable to turnthe sensor on and off.
 3. The person support apparatus of claim 1,wherein the sensor comprises a plurality of sensors and wherein thecontroller operates to control each of the plurality of sensors by atleast one of changing a gain of each of the plurality of sensors andchanging a manner in which signals from each of the plurality of sensorsis filtered.
 4. The person support apparatus of claim 1, wherein thesensor comprises a plurality of sensors, the controller operates to turnoff some of the plurality of sensors, and the controller operates toturn on others of the plurality of sensors.
 5. The person supportapparatus of claim 4, wherein the determination by the controller as towhich sensors are turned off and which sensors are turned on is based ona position of the person relative to the support surface.
 6. The personsupport apparatus of claim 4, wherein the determination by thecontroller as to which sensors are turned off and which sensors areturned on is based on a position of the person relative to the frame. 7.The person support apparatus of claim 4, wherein the determination bythe controller as to which sensors are turned off and which sensors areturned on is based on movement of a first portion of the frame relativeto a second portion of the frame.
 8. The person support apparatus ofclaim 1, wherein the controller is operable to implement via software atleast one of a high pass filter, a low pass filter, and a band passfilter.
 9. The person support apparatus of claim 1, wherein thecontroller is operable to filter out noise associated with at least oneof a first electric component associated with the support surface and asecond electric component associated with the frame.
 10. The personsupport apparatus of claim 1, wherein the controller is operable tofilter out noise associated with separate medical equipment in aperson's room based on information received from an electronic medicalrecord (EMR) system.
 11. The person support apparatus of claim 1,wherein the controller is operable to selectively switch the sensorbetween being coupled to a high pass filter, a low pass filter, and aband pass filter.
 12. The person support apparatus of claim 1, whereinthe sensor comprises one of a force sensing load cell coupled to theframe and a pressure sensing strip coupled to the support surface. 13.The person support apparatus of claim 1, wherein the support surfacecomprises a mattress having inflatable bladders and the sensor comprisesa pressure sensor that measures pressure in at least one of thebladders.
 14. The person support apparatus of claim 1, wherein thecontroller adjusts the gain of the sensor as a function of a differencebetween a first position of the person relative to one of the frame andthe support surface and a second position of the person relative to oneof the frame and the support surface.
 15. The person support apparatusof claim 1, wherein the sensor senses at least one of the person'sweight, heart rate, respiration rate, and temperature.
 16. The personsupport apparatus of claim 1, wherein the controller is operable toprevent a user from accessing predetermined functions of the personsupport apparatus based on at least one of signal strength and clarityof a signal from the sensor.
 17. The person support apparatus of claim1, wherein the sensor comprises a plurality of sensors and wherein thecontroller controls the gain of each of the plurality of sensors suchthat signal strength of an output signal of each of the plurality ofsensors is substantially equal.
 18. The person support apparatus ofclaim 1, wherein the sensor comprises a first sensor and a second sensorand wherein the controller operates to amplify a signal from the firstsensor when signal strength of the signal from the first sensor is lessthan that of the second sensor.
 19. The person support apparatus ofclaim 1, wherein the sensor comprises a first sensor and a second sensorand wherein a signal from the first sensor is filtered when signalclarity of the signal from the first sensor is less than that of thesecond sensor.
 20. The person support apparatus of claim 1, wherein theat least one characteristic associated with the person comprises atleast one of a force profile, a pressure in a bladder, and aphysiological characteristic.